line.hh

// Copyright (C) 2007, 2008, 2009 EPITA Research and Development Laboratory (LRDE)
//
// This file is part of Olena.
//
// Olena is free software: you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation, version 2 of the License.
//
// Olena is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Olena.  If not, see <http://www.gnu.org/licenses/>.
//
// As a special exception, you may use this file as part of a free
// software project without restriction.  Specifically, if other files
// instantiate templates or use macros or inline functions from this
// file, or you compile this file and link it with other files to produce
// an executable, this file does not by itself cause the resulting
// executable to be covered by the GNU General Public License.  This
// exception does not however invalidate any other reasons why the
// executable file might be covered by the GNU General Public License.

#ifndef MLN_ACCU_LINE_HH
# define MLN_ACCU_LINE_HH


# include <mln/core/concept/meta_accumulator.hh>
# include <mln/core/concept/image.hh>



namespace mln
{

  namespace accu
  {

    // FIXME:

    template <typename Meta_Accu, unsigned Dir, // Free parameters.
              typename I, typename O>
    void
    line(const Image<I>& input,
         const mln_site(I)& p_start, unsigned len,
         unsigned half_length,
         Image<O>& output);



# ifndef MLN_INCLUDE_ONLY

    namespace internal
    {

      template <typename Meta_Accu, unsigned Dir, // Free parameters.
                typename I, typename O>
      void
      line_tests(const Image<I>& input_,
                 const mln_site(I)&, unsigned,
                 unsigned,
                 Image<O>& output_)
      {
        mlc_is_a(Meta_Accu, Meta_Accumulator)::check();

        typedef mln_accu_with(Meta_Accu, mln_value(I)) A;
        mlc_converts_to(mln_result(A), mln_value(O))::check();

        typedef mln_site(I) P;
        mlc_bool(Dir < P::dim)::check();

        mlc_is(mln_trait_image_value_io(O),
               mln::trait::image::value_io::read_write)::check();

        const I& input = exact(input_);
        O& output = exact(output_);
        mln_precondition(input.is_valid());
        mln_precondition(output.is_valid());
      }
      
    } // end of namespace mln::accu::internal


    namespace impl
    {

      namespace generic
      {
        
        template <typename Meta_Accu, unsigned Dir,
                  typename I, typename O>
        void
        line(const Image<I>& input_,
             const mln_site(I)& p_start, unsigned len_,
             unsigned half_length_,
             Image<O>& output_)
        {
          typedef mln_site(I) P;
          typedef mln_accu_with(Meta_Accu, mln_value(I)) A;

          const I& input = exact(input_);
          O& output = exact(output_);

          // Avoid warning in signed/unsigned comparison.
          const def::coord len = static_cast<def::coord>(len_);
          const def::coord half_length = static_cast<def::coord>(half_length_);

          // Checks and tests.
          internal::line_tests<Meta_Accu, Dir>(input,
                                               p_start, len,
                                               half_length,
                                               output);

          // Initialization.
          const def::coord start = p_start[Dir];
          const def::coord last = static_cast<def::coord>(start + len - 1);
          A a; // Accumulator.
          a.init();
          P p; // Current point.

          // Start (first line point).
          p = p_start;
          P q = p;
          for (def::coord c = 0; c <= half_length && c < len; ++c)
            {
              a.take(input(q));
              ++q[Dir];
            }
          output(p) = a;

          def::coord& cur = p[Dir];
          if (cur == last)
            return;

          // Begin of line.

          P p_plus = p_start;
          def::coord& plus = p_plus[Dir];
          plus = static_cast<def::coord>(plus + half_length);

          while (cur < start + half_length && cur < last)
            {
              ++cur;
              ++plus;
              if (plus <= last)
                a.take(input(p_plus));
              output(p) = a;
            }

          if (cur == last)
            return;

          // Middle of line.

          P p_minus = p_start;
          def::coord& minus = p_minus[Dir];
          --minus;

          while (cur < last - half_length)
            {
              ++cur;
              ++plus;
              ++minus;
              mln_invariant(plus >= start && plus <= last);
              a.take(input(p_plus));
              mln_invariant(minus >= start && minus <= last);
              a.untake(input(p_minus));
              output(p) = a;
            }

          if (cur == last)
            return;

          // End of line.

          while (cur < last)
            {
              ++cur;
              ++minus;
              mln_invariant(minus >= start && minus <= last);
              a.untake(input(p_minus));
              output(p) = a;
            }
        }

      } // end of namespace mln::accu::impl::generic



      template <typename Meta_Accu, unsigned Dir,
                typename I, typename O>
      void
      line_fastest(const Image<I>& input_,
                   const mln_site(I)& p_start, unsigned len,
                   unsigned half_length,
                   Image<O>& output_)
      {
        typedef mln_site(I)  P;
        typedef mln_value(I) V;
        typedef mln_accu_with(Meta_Accu, V) A;

        const I& input = exact(input_);
        O& output = exact(output_);

        // Checks and tests.
        internal::line_tests<Meta_Accu, Dir>(input,
                                             p_start, len,
                                             half_length,
                                             output);

        // Initialization.

        const def::coord start = p_start[Dir];
        const def::coord last = start + len - 1;

        const V* p_in    = & input(p_start);
        V* p_out   = & output(p_start);

        mln_delta(P) dp = literal::zero;
        dp[Dir] = 1;
        unsigned offset = input.delta_index(dp);

        A a; // Accumulator.
        a.init();

        // Start (first line point).

        const V* q = p_in;
        for (def::coord c = 0; c <= half_length && c < len; ++c)
          {
            a.take(*q);
            q += offset;
          }
        *p_out = a;

        def::coord cur = p_start[Dir];
        if (cur == last)
          return;

        // Begin of line.

        def::coord plus = start + half_length;
        const V* p_plus = p_in + half_length * offset;

        while (cur < start + half_length && cur < last)
          {
            ++cur;
            p_in += offset;
            ++plus;
            p_plus += offset;
            if (plus <= last)
              a.take(*p_plus);
            p_out += offset;
            *p_out = a;
          }

        if (cur == last)
          return;

        // Middle of line.

        def::coord minus = start - 1;
        const V* p_minus = p_in - offset;

        while (cur < last - half_length)
          {
            ++cur;
            p_in += offset;
            ++plus;
            p_plus += offset;
            ++minus;
            p_minus += offset;
            mln_invariant(plus >= start && plus <= last);
            a.take(*p_plus);
            mln_invariant(minus >= start && minus <= last);
            a.untake(*p_minus);
            p_out += offset;
            *p_out = a;
          }

        if (cur == last)
          return;

        // End of line.

        while (cur < last)
          {
            ++cur;
            p_in += offset;
            ++minus;
            p_minus += offset;
            mln_invariant(minus >= start && minus <= last);
            a.untake(*p_minus);
            p_out += offset;
            *p_out = a;
          }

      }




    } // end of namespace mln::accu::impl


    namespace internal
    {

      template <typename Meta_Accu, unsigned Dir, // Free parameters.
                typename I, typename O>
      void
      line_dispatch(trait::image::speed::any,
                    const Image<I>& input,
                    const mln_site(I)& p_start, unsigned len,
                    unsigned half_length,
                    Image<O>& output)
      {
        impl::generic::line<Meta_Accu, Dir>(input,
                                            p_start, len,
                                            half_length,
                                            output);
      }

//       template <typename Meta_Accu, unsigned Dir, // Free parameters.
//              typename I, typename O>
//       void
//       line_dispatch(trait::image::speed::fastest,
//                  const Image<I>& input,
//                  const mln_site(I)& p_start, unsigned len,
//                  unsigned half_length,
//                  Image<O>& output)
//       {
//      impl::line_fastest<Meta_Accu, Dir>(input,
//                                         p_start, len,
//                                         half_length,
//                                         output);
//       }

      template <typename Meta_Accu, unsigned Dir, // Free parameters.
                typename I, typename O>
      void
      line_dispatch(const Image<I>& input,
                    const mln_site(I)& p_start, unsigned len,
                    unsigned half_length,
                    Image<O>& output)
      {
        line_dispatch<Meta_Accu, Dir>(mln_trait_image_speed(I)(),
                                      input,
                                      p_start, len,
                                      half_length,
                                      output);
      }
      
    } // end of namespace mln::accu::internal


    template <typename Meta_Accu, unsigned Dir, // Free parameters.
              typename I, typename O>
    void
    line(const Image<I>& input,
         const mln_site(I)& p_start, unsigned len,
         unsigned half_length,
         Image<O>& output)
    {
      internal::line_tests<Meta_Accu, Dir>(input,
                                           p_start, len,
                                           half_length,
                                           output);
      internal::line_dispatch<Meta_Accu, Dir>(input,
                                              p_start, len,
                                              half_length,
                                              output);
    }

# endif // ! MLN_INCLUDE_ONLY

  } // end of namespace mln::accu

} // end of namespace mln


#endif // ! MLN_ACCU_LINE_HH